The invention relates to seats in general, especially to seats for use in motor vehicles. More particularly, the invention relates to improvements in back rests which can be used with advantage in the seats of motor vehicles. Still more particularly, the invention relates to back rests of the type having adjustable shoulder supports or shoulder rests, namely shoulder-engaging portions which are adjustable with reference to the frames of back rests in order to afford more comfort to the occupants.
German Pat. No. 23 56 982 to Strien et al. discloses a back rest with a relatively short shoulder rest which is pivotally secured to the upper portion of the frame of the back rest. The patented back rest further comprises means for releasably holding the shoulder rest in any one of a rather limited number of different positions. A drawback of the patented back rest is that the distance of the pivot axis from the topmost portion of the shoulder rest is very short. This entails pronounced changes in orientation of the shoulder rest with reference to the frame of the back rest in response to relatively small angular displacements of the shoulder rest about the pivot axis.
German Pat. No. 27 27 948 to Goldner discloses a modified back rest wherein the shoulder rest can be moved to an infinite number of different positions relative to the frame of the back rest. However, the proposal of Goldner exhibits the same drawbacks as that of Strien et al., i.e., the pivot axis for the relatively short shoulder rest is closely adjacent the topmost portion of the shoulder rest so that each pivotal movement of the shoulder rest entails a very pronounced change in orientation relative to the frame of the back rest. It has been found that the solutions which are proposed in the aforediscussed patents are not entirely satisfactory because it can happen that the cushion which overlies the shoulder rests of the patented seats will be in mere linear contact with the shoulders of the occupant in numerous angular positions of the shoulder rest. Such linear contact is uncomfortable to the occupant.